Abstract.A total of 104 children with allergic bronchial asthma were included in studies comparing the results of RAST and skin testing with each other and with the results of bronchial challenges using different concentrations of extracts of Cladosporium herbarum. Prick tests predicted bronchial allergy to the mould in 83–96% of the cases compared to 74–83% for RAST predicting such bronchial allergy. Bronchial reactions to top concentrations of the extracts were considered immunologically non‐specific and probably due to contents of irritants in most inst